It won’t blow you away, but you can’t beat the price at Park Lane Hotel and Suites (12 Park Ln., 843/686-5700, www.hiltonheadparklanehotel.com [1], $120). This is your basic suite-type hotel (formerly a Residence Inn) with the basic free Continental breakfast. The allure here is the price, hard to find anywhere these days at a resort location. For a non-refundable $50 fee, you can bring your pet.
The one drawback, probably reflected in the price, is that the beach is a good ways away. The hotel does offer a free shuttle, however, so it would be wise to take advantage of that and avoid the usual beach parking hassles.
Links:
[1] http://www.hiltonheadparklanehotel.com